The hunt for water on the moon has lasted for decades. This year, three separate spacecraft found evidence that water may in fact be widespread, clinging to the lunar soil. Hydrogen in the solar wind is thought to create the water when it collides with oxygen-rich materials on the lunar surface. Although the water exists in trace amounts, some researchers suspect it could be harvested by heating the soil with microwaves.

The moon's biggest cache of water may lie at the poles. Bucketfuls of the stuff were kicked up in October, when NASA's LCROSS satellite sent a spent rocket stage crashing into a permanently shadowed crater on the moon's south pole. (Illustration: University of Maryland/F. Merlin/McREL)